Natural Remedies for Sweet Corn Blight

Young corn plants are more susceptible to sweet corn blight than mature plants.

Stewart’s wilt and blight of sweet corn, commonly called sweet corn blight, is caused by a bacteria that feeding corn flea beetles carry in their innards. The bacteria can kill sweet corn seedlings less than 2 feet tall. There is nothing you can do to suppress the disease once it gets started, but there are natural remedies a home gardener can use to control corn flea beetles.

Symptoms

Yellowish streaks develop on older leaves of young plants, eventually turning brown. On mature plants, irregular, yellowish to pale green streaks with wavy edges sometimes extend half the length of a leaf, and can usually be traced to flea beetle wounds on the upper half. If you cut a wilted or dying plant that has a normal stalk, you’ll encounter yellowish bacterial ooze. While you can grow corn in U.S. Department of Agriculture plant hardiness zones 5 through 8, sweet corn blight is typically not found in dry climates, and only in areas with corn flea beetles.

Trap Crop

Flea beetles love “Southern Giant” mustard (Brassica juncea “Southern Giant”) more than they do sweet corn. Plant “Southern Giant” as a trap crop along the edge of your corn seedlings to lure corn flea beetles away. Sow the mustard seeds about two weeks before you plant your corn, and when the corn has five or six true leaves, pull the mustard plants and destroy them. Your trap crop should be about 1 percent of the size of your corn crop. “Southern Giant” mustard is an annual plant.

Other Organic Solutions

While insecticidal soap might sound dubious for organic growing, it is not. It contains environmentally safe fatty acids as part of the soap that coats the protective covering of flea beetles, eventually smothering them. You spray it on, but for it to work you have to douse the flea beetles. You can also dust them with diatomaceous earth, a mineral powder that cuts into their exterior shells and causes them to dry out. Wear a mask and goggles when you apply diatomaceous earth so you won’t inhale it or get it in your eyes.